High tenacity rayon yarn production



United States Patent 3,364,290 HIGH TENACITY RAYON YARN PRODUCTION GcertAntenna, Tietso Knipers, and .lohannes .l'. M. Mulderink, Arnhem,Netherlands, assignors to American Erika Corporation, Elliifi, N.C., acorporation of Delaware No Drawing. Filed Oct. 25, 1963, Ser. No.318,838 Claims priority, application Netherlands, Oct. 39, 1962, 284,8887 Claims. (Cl. 264-191) ABSTRACT OF THE DISCLGSURE Manufacture of hightenacity rayon yarns comprising the process of extruding a viscosecontaining a skinproducing modifier and a cation-active compound whichcounteracts the occurrence of spinning faults into a spin bathcontaining sulfuric acid, sodium sulfate and zinc sulfate, stretchingthe yarn in a hot dilute acid bath, adjusting the yarn to a pH of fromto 8.5, collecting the yarn in the form of a cake, unwinding the yarnfrom the cake, after-stretching and drying the yarn for a maximum of 20minutes.

This invention relates generally to the production of rayon filamentarymaterials suitable for use as reinforcement in tires, belts and otherrubber articles and more particularly to a process for producing extrahigh tenacity threads, yarn, and cord of regenerated cellulose.

The known process for producing high tenacity regen erated cellulosethreads, yarn and cord, hereinafter referred to colectively as yarn,comprises extruding a viscose in the presence of a skin-producingmodifier, into a spinning bath containing sulfuric acid, sodium sulfate,and 3 to 10% by weight of zinc sulfate, stretching the freshly spun yarnin a hot bath containing dilute acid, collecting and winding thestretched yarn in package form, and drying the yarn in the package orunwinding and drying it continuously. The thus produced yarn has a hightenacity, each filament having a high skin structure when viewed incross section.

It has been found that rayon yarn of even higher tenacity than thatproduced by the aforementioned process is desirable for many present dayapplications. In this respect then, While the known high tenacity yarnis generally good, it is necessary that even higher tenacity yarn beproduced.

Accordingly, it is an object of this invention to provide a process forproducing rayon yarn having improved properties.

Another object of this invention is to provide a process for producingextra high tenacity rayon yarn.

Still another object of this invention is to provide a process forproducing extra high tenacity yarn of regenerated cellulose that can becarried out in conjunction with the known process with a minimum ofadditional steps and attendant expense.

These and other objects will become more apparent from the followingdetailed description.

In accordance with the present invention, extra high tenacity rayon yarnis produced by modifying the aforementioned known process with twocritical steps. In essence, this comprises adjusting the extruded yarnto a pH of 5 to 8.5 after stretching in the hot acid bath and beforewinding, followed by limiting the drying process to a maximum ofminutes.

There are several methods of adjusting the freshly spun wet yarn to a pHof 5 to 8.5. A Very simple method consists in washing the running wetyarn with water. If water is used having a temperature of 13 C. orhigher, then it is preferred to prolong the treatment of the wet yarnuntil they no longer contain salts and the pH of the yarn is about 7. Ifcold water is used, i.e., 12 C. or lower, then the wet yarn need not betreated until it is free from salts.

The pH of the yarn is determined as follows: 200 cc. distilled water ispoured over 6 grams of the wet yarn (containing about moisture) in abeaker. The yarn is allowed to stand in the beaker for one hour, withoccasional shaking, after which the pH of the liquid is measured,thereby determining the pH of the yarn.

In addition to water, the treatment of the wet yarn can be carried outwith an aqueous salt solution such as sodium carbonate, sodiumbicarbonate, or sodium sulfate. An aqueous solution of ammonia may alsobe used. If the temperature of the washing liquid is 12 C. or lower,then the yarn need not be washed as thoroughly as when the temperatureis 13 C. or higher. The treatment of the wet yarn with water,salt-containing water, or ammoniacal water may be carried out by passingthe yarn through a bath. As pointed out above, however, it is criticalthat this step be carried out before the yarn is wound and collected inpackage form. Alternately, the liquid can be sprayed on the godet overwhich the yarn is passed to the collecting device.

After the wet yarn has been treated so that its pH is from 5 to 8.5, itis collected in a yarn package such as in a spinning pot, perforatedbasket, or on a spool. It is thereafter dried and, as mentioned above,the drying process must not last longer than 20 minutes. A drying periodof any longer duration has a very unfavorable influence on the tenacityof the yarn. Drying may be carried out by several ways, such as byplacing the wet yarn package in a high-frequency electric field, or byunwinding the wet yarn from the package and drying it with hot air whiletraveling through a drying tunnel. It also may be done by passing thewet yarn over a hot roller.

The yarn should be kept under tension during drying. This may beeflected in various ways. After treatment with the washing liquid, thewet yarn may be Wound under tension on a spool and the yarn packagedried in a high-frequency field. Also, after the treatment with thewashing liquid, the running wet yarn can be guided under tension througha drying tunnel or over a hot roller. In an alternate system, the wetyarn may be unwound from a yarn package, after-stretched, andsubsequently dried.

In a typical process according to the invention, a viscose is spun inthe presence of at least one compound which will produce a skinstructure in the threads. For the sake of brevity, such compounds arehereinafter referred to as modifiers. The modifier may be present in theviscose or in the spin bath, or in both. A number of known modifiers canbe used in the process, such as amines, quaternary ammonium compounds,carbaminates, polyethylene glycol, and ethers having the formula RO(CHCH O),,R', where R is an alkyl or aryl group, R is hydrogen, an alkyl oraryl group, and n is 14 incl. Specific examples of amines arecyclohexylamine, quinoline, ethylene diamine, hexamethylene diamine,dipropylene triamine, dodecylarnine, and dibutylaminopropylamine.Examples of quaternary ammonium compounds are benzyltrimethylammoniumhydroxide, tetraethylammonium hydroxide, tetraethylammonium bromide,tetraethylammonium iodide, and tributylpropylammonium peroxide.Representative carbaminates are sodiumcyclohexyldithiocarbaminate,sodium phenyldithiocarbaminate, sodium morpholyl-N-dithiocarboxylate,and sodium-cyclohexylmonothiocarbaminate. The polyethylene glycol mayhave an average molecular weight of 200 to 4,500. Examples of others arephenoxyethanol, ethoxyethanol, methoxyethoxyethanol, andbutoxyethoxyethanol. The modifiers may be used singly or in combination.

For best results, it is also preferred to spin the viscose in thepresence of a compound which counteracts the occurrence of spinningfaults. These are usually cationactive compounds, for example,laurylpyridiniurn chloride, stearylpyridinium chloride,dodecyltriethylammonium iodide, and compounds having the formula:

(C 21140) H RN\ (C 21140) yH where R is an alkyl group having 8 to 24carbon atoms, x and y are at least 1, and x-l-y is to 25. Preferably, aviscose is used containing the last mentioned compound in combinationwith polyethylene glycol. The viscose contains each of these twosubstances in amounts of at least 0.5% by weight, based on the cellulosein the viscose, with the nitrogen compound being derived from soy beanoil, coconut oil, or tallow, and where x plus y is about 12.

When using these two compounds in combination, the yarn obtained hasoptimum strength if the viscose employed has a cellulose content of 6 to8% by weight, a total alkali content of 5 to 6% by weight, and aHottenroth maturity index of 13 to 18. The viscose should then beextruded into a spin bath maintained at 40 to 60 C.,' having a sulfuricacid content in percent by weight which is 0.83 to 0.95 times the totalalkali content in percent 7 by weight of the viscose, a sodium sulfatecontent of 11 to 15% by weightjand a zinc sulfate content of 3 to 5% byweight. The yarn is then successively stretched about 100% in a dilutesulfuric acid bath maintained at about 95 C., washed with water until itis free of acid and salts, and collected in the form of a cake in aspinning pot. The yarn is then unwound from the cake and after-stretchedabout It is subsequently dried on a hot roller and thereafter wound inpackage form.

To further illustrate the invention, the following examples are given.However, the invention is not intended to be limited thereby. Allpercentages are by weight unless otherwise stated.

Example I A viscose is prepared having a cellulose content of 7.3%, atotal alkali content of 5.5%, a viscosity of 110 seconds (ball fallmethod), and containing 1.5% by weight (based on the cellulose in theviscose) of polyethylene glycol having an average molecular weight of3,000, and 1.5% by weight (based on the cellulose in the viscose) of acompound having the formula:

(0211.0),11 where R is an alkyl radical derived from coconut oil, andx+y is 12. The viscose was aged to a -number of 45 and a Hottenrothmaturity index of and spun into a bath maintained at 50 C. containing4.9% sulfuric acid, 13% sodium sulfate, 4.5% zinc sulfate, 0.004%

laurylpyridiniurn chloride, and 0.025% of a compound having the formula:

where R is an alkyl radical derived fromv coconut oil, and x-I-y is 12.The spinneret had 1,000 orifices, each having a diameter. of 60p. Theyarn emerging therefrom was guided through a tube immersed in the spinbath which consisted of two cylindrical sections, one section (near thespinneret) having an inner diameter of 16.5 mm. and the second having aninner diameter of mm. The yarn was taken up by means of a godet at 30m./ min.

After the yarn had left the spin bath, it was passed through a secondbath maintained at 95 C. containing 2.5% sulfuric acid, 1% sodiumsulfate, and 0.5% zinc sulfate. In this bath the yarn was stretched bymeans of a second godet, the speed of which was twice that of the firstgodet. Water at 30 C. was sprayed on the second godet. After the yarnhad left the second godet, it had a pH of 7.5 and was collected in aspinning pot. It had obtained a twist of 100 S turns per meter. The thusproduced yarn was then drawn off the cake in the wet state and guidedthrough a water bath containing 3% liquid paraffin, 0.3% butyl stearate,and 0.4% sulfated peanut oil. In this bath the yarn was after-stretchedabout 10% and then dried in half a minute by guiding it, under tension,over a hot roller. The resulting yarn had a denier of 1,650 and waswound onto a spool.

The yarn was conditioned in air at 20 C. and 60% relative humidity andhad a strength of 9.6 kg. Desulphurization, washing and drying of theyarn did not produce any decrease in strength. Thereafter, the yarn wastwisted 470 S turns per meter. Two such yarns were plied together with470 Z turns per meter to produce a tire cord that had, in theconditioned and bone-dry state, a strength of 15.1 and 18.5 kg,respectively.

Example 11 The process of Example I was repeated, except that the yarnwas not treated with water on the second godet.

After the yarn had been collected in the spinning pot, it wasdesulphurized and washed. Subsequently, the yarn was after-stretched byabout 10% in the sizing bath and then dried. The conditioned strength ofthe yarn was 8.2 kg., considerably lower than that of the yarn obtainedin the process described in Example I. The conditioned strength and thebone-dry strength of tire cord made from two such yarns were 13.5 and15.9, respectively.

Example III The process of Example I was repeated, except that on thesecond godet the yarn was sprayed with water at 12 C. After the yarn hadbeen collected in the spinning pot, it was successively desulphurized,washed, afterstretched by about 10% in the wet state, dried on a hotroller, and wound. The conditioned strength of the yarn was 9.6 kg. Theconditioned strength and the bonedry strength of tire cord made from twosuch yarns were 15.0 and 18.4 kg., respectively.

Example IV Example V The process of Example I was repeated, except thatthe viscose contained 2% by weight (based on the cellulose in theviscose) quinoline and 1% by weight (based on the cellulose in theviscose) of a compound having the formula:

RN v

(O2H40)yH whereR is an alkyl radical derived from coconut oil and x+y IS12. The conditioned strength of the yarn was 9.4 kg. The conditionedstrength and the bone-dry strength of tire cord made from two such yarnswere 14.9 and 18.2 kg, respectively.

Example VI The process of Example I was repeated, except that theviscose contained 1.5% by weight (based on the cellulose in the viscose)of a compound having the formula:

(C 2H40) yH where R is an alkyl radical derived from coconut oil and x+yis 12, and 1.5% by weight (based on the cellulose in the viscose) of acompound having the formula:

where R is an alkyl radical derived from coconut oil and x+y is 12. Theconditioned strength of the yarn was 9.2 kg. The conditioned strengthand the bone-dry strength of tire cord made from two such yarns were14.8 and 18.0 kg., respectively.

Many modifications and changes within the scope of this invention willbe apparent to those skilled in the art. Accordingly, the invention isintended to be limited only to the extent set forth in the followingclaims.

What is claimed is:

1. In a process for producing high tenacity rayon yarn, the combinationwhich comprises:

(a) extruding a viscose containing at least one skinproducing modifierselected from the group consisting of an amine, a quaternary ammoniumcompound, a carbamate, a polyethylene glycol and an ether having theformula RO (CH CH O R where R is selected from the group consisting ofalkyl and aryl radicals, R is selected from hydrogen, alkyl and arylradicals and n is 1-4 in combination with a cation-active compound whichcounteracts an occurrence of spinning faults, said cation-activecompound being selected from the group of laurylpyridinium chloride,stearylpyn'dinium chloride, dodecyltriethylammonium iodide and compoundshaving the formula where R is an alkyl group having 8 to 24 carbon atomsand x-I-y is 5 to 25, (b) into a spin bath being maintained at 40-60 C.

having a sulfuric acid content in percent by weight which is 0.83 to0.95 times the total alkali content in percent by weight of the viscose,a sodium sulfate content of 11 to 15% by weight and a zinc sulfatecontent of 3 to 5% by weight,

(c) successively stretching the yarn about 100% in a dilute sulfuricacid bath maintained at about C.,

(d) adjusting the yarn to a pH of from 5 to 8.5 and collecting the yarnin the form of a cake,

(e) unwinding the yarn from the cake, and

(f) after-stretching the yarn about 10% and drying for a maximum of 20minutes.

2. The process of claim 1 in which the pH of the yarn is attained bytreating the yarn with water.

3. The process of claim 1 in which the pH of the yarn is attained bytreating the yarn with an aqueous salt solution.

4. The process of claim 1 in which the pH of the yarn is attained bytreating the yarn with an aqueous ammonia solution.

5. The process of claim 1 in which the yarn is dried while undertension.

6. The process of claim 1 in which the viscose contains as modifiers atleast 0.5 by weight based on the cellulose in the viscose ofpolyethylene oxide and at least 0.5% by weight based on the cellulose inthe viscose of a compound having the formula:

(C2H4O)XH (C2H40) H Where R is an alkyl radical containing from 8 to 24carbon atoms and x-l-y is 5-25.

7. The process of claim 1 in which the yarn is afterstretched about 10%and dried on a hot roller.

References Cited UNITED STATES PATENTS 2,512,968 6/1950 Ray 264 1972,611,928 9/1952 Merion 264-197 2,602,258 12/1952 McLellan 264-1982,852,333 9/1958 Cox 6t al. 264-198 X 2,914,376 9/1959 Bibolet et a1.264-198 X 2,978,292 4/1961 Limburg et a1. 264-194 X 2,983,572 5/1961Elling et al. 264-194 X 3,007,766 11/1961 Elssner et a1. 264-194 X3,046,082 7/1962 Mitchell et al 264-194 X 3,046,085 7/1962 Burroughs etal. 264197 X ALEXANDER H. BRODMERKEL, Primar Examiner.

J. H. WOO, Assistant Examiner.

